DESCRIPTION (Applicant's Description): T h e c loning of oncogenes and tumor suppressor genes from genetic translocations or deletions in human tumors has revealed numerous genetic interactions regulating growth whose existence could not have been predicted by biochemical and cell culture analyses. It has become apparent that many of the genes controlling cellular growth in the adult organism also control growth during development. It will be necessary to define these processes on the molecular level before it will be possible to develop intervention strategies for conditions like cancer where normal growth regulation has been abolished. The Neurofibromatosis 2 (NF2) gene is an example of such a tumor suppressor gene, whose identification revealed a new function in growth regulation for cytoskeletal membrane-linker proteins. NF2 is a dominantly inherited disease which combines developmental defects (germline loss of one NF2 allele) with a predisposition for tumor formation (somatic loss of the second NF2 allele). A loss of function in NF2 is also found in sporadic tumors, demonstrating a more widespread role for NF2 as a tumor suppressor. NF2 is structurally related to the ezrin-radixin-moesin (ERM) family of cell junctional cytoskeletal membrane-linker proteins. Originally implicated in cell shape, migration and adhesion phenomena, they may also function in cell-cell contact mediated signal transduction. The applicants have cloned the homologs of NF2 (ceNF2) and a related family member (ceERM) in C. elegans in order to take advantage of a model genetic system in which to study gene interactions affecting growth. They have shown by anti-sense inhibition that ceNF2 and ceERM are essential for embryonic d e v e lopment and post-embryonic morphogenesis and cell proliferation. Furthermore, they have demonstrated for the first time that ceNF2 expression is directly regulated by growth modulating signals transmitted through transmembrane receptors. The goals of this proposal are 1) to resolve the ceNF2/ceERM expression pattern to single cell identification throughout development using promoter expression constructs and Nomarski differential microscopy, (2) to define the subcellular localization of ceNF2/ceERM relative to cell junction proteins and intracellular markers in double antibody staining experiments with confocal microscopy, (3) to characterize previous findings on ceNF2/ceERM effects on embryonic, germline and somatic gonad development by anti-sense inhibition using heat-shock vectors in transgenic animals as well as by direct injection of anti-sense RNA, (4) to conduct an intra-genic screen taking advantage of transgenic lines carrying ceNF2 and ceERM on an extrachromosomal array in order to isolate reduced function and null alleles of ceNF2 and ceERM and (5) to conduct an extra-genic screen with the purpose to discover proteins which mediate the functional interaction of ceNF2 and ceERM with growth regulating signal transduction pathways.